Sheet feed between multiple couple rotary press units



United States Patent [72] lnventors Robert K. Norton Twinsburg, Ohio;

William H. Weidman, Independence, Ohio {21] Appl. No. 636,373. [22] Filed May 5, 1967 [45] Patented Aug. 25, 1970 [73] Assignee l-larris-Intertype Corporation Cleveland, Ohio a corporation of Delaware [54] SHEET FEED BETWEEN MULTIPLE COUPLE ROTARY PRESS UNITS 2 Claims, 1 Drawing Fig.

[52] U.S.Cl 101/136, 101/177, 101/183, 101/232- [51] Int. Cl B4lf7/06 [50] Field ofSearch 101/177, 183,217,232,137,142,184,152, 153,174,216, 218,409, 175, 136

[56] References Cited UNITED STATES PATENTS 367,024 7/1887 Clark et al. 101/174 640,633 1/1900 Corbin 101/175 Primary Examiner Robert E. Pulfrey Assistant Examiner- .1 Reed Fisher Attorneys-Yount, Flynn and Tarolli ABSTRACT: A printing press for printing sheet material at a printing nip formed between an impression cylinder and a printing cylinder. The impression cylinder has a diameter which is an integer multiple of the diameter of the printing cylinder and carries a plurality of grippers at spaced circumferential locations with the number of locations being equal to the diameter multiple of the impression cylinder. Grippers on a transfer cylinder engage a leading edge of the sheet at a transfer location. The transfer location is spaced from the printing nip by a distance along the path of sheet travel which is greater than the maximum sheet length to be printed by the printing press so that the sheet is entirely clear of the printing nip prior to being gripped by the grippers on the transfer cylinder.

Patented Aug. 25, 1970 8 NM R o WW KM WM 1mm /RW SHEET FEED BETWEEN MULTIPLE COUPLE ROTARY PRESS UNITS The present invention generally relates to rotary sheet fed printing presses having printing units comprising three cylinders. In particular, it relates to a novel arrangement and size relationship for these cylinders in a printing unit, and to such arrangement embodied in a multicolored rotary press of known construction.

Printing units of the above type include an impression cylinder, an ink transferring cylinder usually located generally vertically above and spaced from the impression cylinder, and a printing cylinder between and adapted to coact with both the ink transferring and impression cylinders. This type of printing unit has been conventional for a number of years in most lithographic printing presses. In such a press, the ink transferring cylinder is a plate cylinder, and the printing cylinder is a blanket cylinder.

In the operation of a conventional multicolor lithographic printing press, the sheets to be printed are gripped by grippers mounted on the impression cylinder and carried through a printing zone in which the blanket cylinder prints a first color on the sheet. The sheets are then transferred from the impression cylinder to the impression cylinder of the next adjacent printing unit where a second color is to be printed on the sheets by a transfer cylinder having grippers thereon for gripping the printed sheet and carrying the same to the next adjacent impression cylinder. Any number of printing units can be provided and after the last color has been printed on the sheets they are delivered by a delivery cylinder to a delivery mechanism to be deposited on a pile.

in known printing unit arrangements, such as that shown in U.S. Pat. No. 3,1 12,695 to Howard J. Seel, the grippers on the transfer cylinder grip the leading edge of the sheet and begin the transfer operation before its trailing portion leaves the printing nip. This causes the sheet to be placed under tension and have its wet printed side engage the periphery of the transfer cylinder as it is being wrapped therearound, which often results in the print being smudged. To minimize this problem of smudging of the print, multiple size transfer cylinders have been employed, such as that shown in the aforementioned U.S. Pat. No. 3,112,695 to Howard J. Seel. Although the employment of such multiple size transfer cylinders has minimized smudging of the print on the freshly printed side of the sheet during the transfer operation, the use of such transfer cylinders has not been able to eliminate the problem of smudging or to minimize it to the extent deemed satisfactory for some printing operations.

Accordingly, it is an important object of the present invention to provide'a new and improved rotary printing press having a three cylinder printing unit and a sheet transfer or delivery means and which is so constructed and arranged that it overcomes the problem of the print being smudged during the transfer operation.

Another object of the present invention is to provide a new and improved rotary printing press having a three cylinder printing unit in which the impression cylinder is of a larger diameter than the printing cylinder and wherein the printing cylinder and a rotary transfer or delivery means for receiving the sheets from the impression cylinder are disposed relative to one another such that the distance, as measured, peripherally of the impression cylinder, between the printing nip and the transfer nip is greater than the maximum length of sheet which can be printed on the press so that the sheets have their trailing edges free and beyond the printing nip prior to the transfer operation being commenced whereby the sheet is not placed under tension during the transfer operation and the wet printed surface thereon will not be in a tight-wrapped engagement with the sheet transfer means or delivery means.

Another object of the present invention is to provide a new and improved rotary printing press, as defined in the next preceding object, and in which the impression cylinder is a multiple size impression cylinder, preferably a double size impression cylinder.

A further object of the present invention is to provide a new and improved rotary printing press, as defined in the next preceding object, and in which the transfer means carries grippers movable in a circular path having a diameter equal to the diameter of the printing cylinder and has its axis of rotation at substantially the same vertical height as the axis of rotation of the impression cylinder.

A still further object of the present invention is to provide added space between the printing units of multicolor printing press which utilizes double or multiple size impression cylinders and preferably single size transfer means between the units, without changing the length of press or varying the position of the cylinders from one unit to the next.

Other advantages of using a multiple or double size impression cylinder in rotary presses of the character described above are that the sheet handles better on the impression cylinder because the sheet is fully wrapped thereon and bent around a greater radius and because the centrifugal acceleration of the sheet is substantially less than that with a single size impression cylinder. The full wrap configuration of the sheets on the impression cylinder also keeps the sheet more nearly vertical as it approaches the transfer nip and horizontal after the transfer nip whereby blanket slap and strip off bulge are minimized and reduced. Moreover, the use of a double size impression cylinder enables grippers disposed in gaps spaced circumferentially apart thereon to be employed so that the cylinder construction is inherently balanced and symmetrical for better dimensional stability.

Additionally, it should be noted that the employment of a multiple or double size impression cylinder and the arrangement of these respective cylinders enables a skinless single size transfer means to be used. The use of a single size transfer means is not only more economical, but makes sheet handling easier because the centrifugal acceleration is twice as much on such a transfer means as opposed to the double size transfer cylinder heretofore employed. Also, the transfer means may have its axis of rotation at approximately the same height as the axis of rotation of the impression cylinder so as to provide for an increased space between the units of multicolor printing press without changing the length of the press or varying the positions of the cylinder from one unit to the next.

It is also conventional practice in a rotary lithographic printing press to sequentially move the blanket cylinder into and out of contact with the other two cylinders by first moving the blanket cylinder into engagement with the plate cylinder and next with the impression cylinder when printing pressure is thrown on, and to move it out of contact with the plate cylinder and then out of contact with the impression cylinder when the pressure is thrown off. The impact of the blanket cylinder on the sheet when the latter is moved into engagement with the impression cylinder when printing pressure is thrown on often contributes to the formation of print disturbances. The print disturbances are caused by the momentary shock in the gear train of the press and by the impact velocity of the blanket cylinder hitting the sheet. As disclosed in the aforementioned U.S. Pat. No. 3,112,695 to Howard J. Seel, the print disturbances due to the momentary shock in the gear train of the press can be overcome or substantially overcome by locating the plate and ink transferring cylinders such that the printing zone is on the approach side of a vertical plane passing through the rotational axis of the impression cylinder. However, print disturbances due to the impact velocity of the blanket cylinder hitting the sheet still occasionally occur. It has been found that by employing a double size impression cylinder, the blanket lead edge impact speed, i.e., the component of the speed parallel to the line passing through the centers of the impression and printing cylinders at which the blanket lead edge and the sheet hit each other, is substantially reduced over the blanket lead edge impact speed when using a single size impression cylinder and thus, the occurrence of print disturbances due to the impact of the blanket cylinder hitting the sheet is eliminated or further minimized.

Other objects, novel characteristics, and advantages of this invention will be apparent in the following detailed description and in the accompanying drawing, which illustrates a fragmentary side elevational view of certain portions of a printing press embodying certain aspects of the present invention forming a part of the present specification.

The present invention provides a rotary sheet fed printing press having printing units comprising three cylinders and in particular, to a novel arrangement and diameter size relationship of the cylinders in the printing unit as embodied in a mu]- ticolored rotary press of known construction. Although the provisions of the present invention are susceptible to use in various kinds of rotary sheet fed printing presses, they are especially adapted for use in a rotary lithographic printing press, and for the purposes of illustration are herein shown as embodied in a multicolor rotary lithographic printing press 10.

Referring to the drawing, a sheet to be printed by the multicolor printing press is fed from right to left on an inclined feed table 12 by conventional drive tapes (not shown). The sheet is front and side registered while on the feed table 12 and is then advanced in registered position to a rotatable feed cylinder 14. The feed cylinder 14 has grippers 16 for gripping the sheet and transfers the sheet to grippers 18 of a rotatable advance cylinder 20.. The grippers 18 of the advance cylinder 20 carry the sheet and transfer the same to grippers 22 on a rotatable impression cylinder 24 of a first printing unit, generally designated by reference character A. The grippers 22 carry the sheet through a printing zone in which the sheet is printed between the impression cylinder 24 and a rotatable cooperating blanket cylinder 26 having an image on a conventional blanket.

The grippers 22 on the impression cylinder 24 after carrying the sheet through the printing zone in which a first color is printed thereon carry the sheet to a transfer zone in which the leading edge of the sheet is gripped by grippers 30 of a rotary transfer means 32. The sheet is transferred by the transfer means 32 to the grippers 22 of the impression cylinder 24 of the next adjacent printing unit, generally designated by reference character B. The grippers 22 on the impression cylinder 24 of the printing unit B carry the sheet through a printing zone in which a second color is printed thereon and then to a transfer zone in which it is gripped by grippers 38 mounted on each of several gripper assemblies carried on space continuous chains 42 of a sheet delivery mechanism 44. The sheet is taken by one of the gripper assemblies to a position over a delivery pile (not shown), at which point it is released to drop onto the top of the pile. The chains 42 travel around sprockets 46 carried at the ends of a delivery cylinder 48. Although the press 10 is shown on the drawing as having only two printing units, it will of course be understood that more than two units could be provided.

Each of the printing units A and B of the lithographic press shown in the drawing are of an identical construction and arrangement and comprise the impression cylinder 24, the blanket cylinder 26, a plate cylinder 50, an inker 52 and a dampening unit 54. The plate cylinder 50 carries the usual lithographic plate which receives ink from the inker 52 and transfers it to the blanket of the blanket cylinder 26. The inker 52 and the dampening unit 54 may be of any conventional type, but it is preferred that the entire inker be located generally over the plate cylinder, and that the dampening unit be relatively narrow in a horizontal direction.

As shown in the drawing, the plate cylinder 50 is preferably disposed vertically above the blanket cylinder 26 such that their axes of rotation lie in a common vertical plane and that the plate and blanket cylinders are offset toward the feed end of the press relative to the impression cylinder 24. By offsetting the blanket cylinder 26 toward the feed end of the press relative to the impression cylinder 24, a substantial reduction in print disturbances is effected, as more fully described in the aforementioned US. Pat. No. 3,112,695 to Howard J. Seel.

The impression cylinders 24 of the printing units A and B are preferably twice the diameter of the blanket and plate cylinders 26 and 50 of the printing units A and B, but may be any multiple thereof. The impression cylinders 24 have two sets of grippers 22, which are spaced apart with each set of grippers 22 receiving a sheet from the grippers 18 of the advance cylinder 20. The impression cylinders 24 are provided with diametrically opposed gaps in their outer periphery in which the sets of grippers 22 are adapted to be mounted. lf impression cylinders are employed having a diameter which is a multiple greater than two, it will, of course, be understood that the sets of grippers 22 will be located at equally spaced circumferential locations thereon with the number of sets of grip pers and locations being equal to the diameter multiple of the impression cylinder with respect to that of the blanket cylinder 26.

The rotary transfer means 32 preferably has an effective diameter which is equal to .the diameter of the blanket cylinder or one-half the double diameter of the impression cylinder 24. The transfer means 32 can be a conventional transfer cylinder, but is preferably a skinless assembly comprising a rotatable shaft 58 and a plurality of radially extending arms 60 which carry the grippers 30 at their outer end for gripping the sheets at the transfer zone from the impression cylinder 24.

As shown on the drawing, the center or axis of rotation of the rotary transfer means 32 is at substantially the same height, though located slightly below, as the center or axis of rotation of the impression cylinder 24. The relative disposition of the transfer means 32 relative to the blanket cylinder 26 is such a plane containing the axes of rotation of the blanket and impression cylinders 26 and 24 intersects a plane containing the axes of rotation of the transfer means 32 and the impression cylinder 24 to define a large included obtuse angle a therebetween. The included obtuse angle a is slightly less than 180 and preferably approximately l47.5.

It has been found that by providing a double diameter size impression cylinder and the aforementioned relative dispositions of the blanket cylinder 26 and the rotary transfer means 32, that smudging of the wet printed sides of the sheets as they are transferred by the transfer means 32 between adjacent impression cylinders 24 of the printing units A and B can be eliminated or substantially eliminated and that greater access room between adjacent printing units can be provided. Smudging of the wet side of the sheet is eliminated or substantially eliminated because the distance, as measured peripherally of the impression cylinder 24 in the direction of rotation of the latter, between the print line at the printing nip, i.e., the nip between the impression and blanket cylinders, and the transfer line at the transfer nip, i.e., the nip between the transfer means 32 and the impression cylinder 24, is greater than the maximum length of sheet which can be handled or printed by the printing press so that the sheets have their trailing edges free and beyond the printing nip prior to being gripped by the grippers 30 of the transfer means 32. Since the distance between the printing and transfer nips is greater than the maximum sheet length which can be printed or handled by the printing press, the sheet when gripped by the grippers 30 of the transfer means 32 will not be placed under tension and thus, the wet printed side of the sheet will not be pulled into tight-wrapped engagement with the transfer means 32. In fact, the construction and arrangement of the printing units A and B is such that a skinless transfer means or cylinder, which is of a simpler and more economical construction than a conventional transfer cylinder with a smooth skin, can be employed. Moreover, since the sheets are not placed under tension less picking and tearing of the sheets occurs and less coating flaking of the sheets occurs whereby the blanket cylinder and press require less cleaning.

The use of a double or multiple diameter size impression cylinder 24 provides for less sheet bend due to its larger radius, and provides for better sheet handling on the impression cylinder due to the fact the sheets more fully wrap around the impression cylinder 24 and the centrifugal acceleration of the sheet is only half as much as the centrifugal acceleration of the sheet with the use of a single diameter size impression cylinder. Sheet handling is also facilitated during the transfer operation by the employment of a single diameter size transfer means 32 because the centrifugal acceleration of the sheets will be twice as much on the transfer means as it was on the impression cylinder. Additionally, since the impression cylinder has a pair of gaps at diametrically opposed locations and sets of grippers mounted in each of the gaps, it is inherently better balanced and more symmetrical. Moreover, the relatively full-wrap configuration of the sheets on the impression cylinder and the relative disposition of the impression cylinder and the transfer means 32 or delivery cylinder keep the sheet more nearly vertical before the transfer nip and horizontal after the transfer nip. This aids in the reducing blanket cylinder slap and strip off bulging of the sheet as the trailing edge thereof moves through the printing nip.

Regarding the increased operator access, it will be noted that between each pair of adjacent printing units A and B, a section 62 of a platform 64 may be hinged and moved between upper inoperative and lower operative positions. By placing the blanket and plate cylinders vertically above one another, they now occupy space directly below the dampening unit 54 and inker 42 and thus, are considerably more compact in horizontal direction. Also, by locating the plate and blanket cylinders 50 and 26 with respect to the impression cylinder 24 on the feeding end of the press and employing a double size impression cylinder, increased room for the operator between the adjacent printing units A and B is provided.

The blanket cylinder 26 is adapted to be sequentially moved into and out of contact with the plate and impression cylinders 50 and 24 by first moving the blanket cylinder 26 into engagement with the plate cylinder, next with the impression cylinder when printing pressure is thrown on, and to move it out of contact with the plate cylinder 50 and then out of contact with the impression cylinder 24 when the pressure is thrown off. Each of the blanket and plate cylinders are provided with a circumferential gap which usually occupies between 60 and 100 of the periphery of the cylinder. The gaps are timed to come adjacent to each other at the nip of the respective cylinders, and therefore the blanket cylinder gap will coincide with the plate cylinder and the impression cylinder gap at different times of each press cycle. Any suitable type of throw-off mechanism, for example, the one described in US. Pat. No. 2,773,445 to J. R. Wood, can be employed to effect the sequential throwing off and on of the blanket or printing cylinder with respect to the other two cylinders.

The blanket lead edge impact speed, which is the relative speed parallel to the line of centers of the blanket and impression cylinders at which the blanket lead edge and sheet hit each other when printing pressure is thrown on, is substantially reduced when a double diameter size impression cylinder is employed as opposed to the employment of an impression cylinder having a diameter equal to the diameter of the blanket cylinder. It has been found that this reduction in the impact velocity of the blanket cylinder 26 on the sheets eliminates or minimizes print disturbances resulting from the impact of the blanket cylinder on the sheets as the blanket cylinder is moved into engagement with the sheet.

As shown in the drawing, the cylinders of the printing press 10 are drivingly interconnected by direct gear drives and are all rotated at the same peripheral speed.

The utilization of a double size impression cylinder and the arrangement of the blanket and plate cylinders 26 and 50 with respect to the impression cylinder 24 provides access to the impression cylinder 24 for a slitting wheel 70 and its support (not shown). The slitting wheel 70 may be of any conventional type and usually cooperates with a hardened steel band which is wrapped around the last impression cylinder.

While the invention is particularly useful in the lithographic rotary printing presses, it has similar advantages also in a socalled Wrap-around (trademark) letter press in which the space occupied by the blanket cylinder herein lS occupied by a plate cylinder of such letter press and in which the space herein occupied by the plate cylinder is occupied by a large inking drum of the inker. It is customary in presses of both these types to provide conventional bearers between the cylinders 26 and 50. These bearers-are located at the end of the cylinders and are urged towards each other with a preselected pressure force to maintain substantial rigidity of the printing units.

Various modifications may be made in the details of construction and in the type of printing press with which the invention is used without departing from the spirit and scope of the present invention.

We claim:

1. In a multi-color printing press for printing sheet material, a plurality of spaced printing units, each of said printing units comprising an impression cylinder and a blanket cylinder cooperating to form a printing nip therebetween on an approaching side of a vertical plane passing through the axis of rotation of said impression cylinder and being operable to print sheets having a length up to the maximum sheet length which can be printed by the cylinders, each of said impression cylinders having a diameter which is a whole integer multiple greater than one of the diameter of the cooperating blanket cylinder and carrying a plurality of grippers at spaced circumferential locations with the number of locations being equal to the diameter multiple of the impression cylinder, said grippers carried by said impression cylinders being operable to advance a sheet through said printing nips when said impression cylinders are rotated, a sheet transfer cylinder disposed between adjacent printing units and having a diameter which is less than the diameters of said impression cylinders, said transfer cylinder being rotatable and having grippers for gripping the sheet at its leading edge at a transfer location from the impression cylinder of one printing unit and transferring the same to the impression cylinder of the next printing unit, said impression cylinders of said printing units having their axes of rotation lying in a common horizontal plane, said transfer location being spaced from the printing nip of said one printing unit a distance along the path of sheet travel which is greater than said maximum sheet length whereby all sheets are entirely clear of the printing nip of said one printing unit prior to being gripped by the grippers of said transfer cylinder.

2. In a rotary printing press as defined in claim 1 wherein each of said impression cylinders has a diameter twice that of the cooperating blanket cylinder and carries sheet grippers spaced circumferentially apart thereon and said transfer cylinder has a diameter equal to that of said blanket cylinders. 

